The authors investigated the impact of a manualized high school transition program, the Peer Group Connection (PGC) program, on the graduation rate at a low-income, Mid-Atlantic high school. The program utilized 12th-grade student peer leaders to create a supportive environment for incoming ninth-grade students. Results of a randomized control trial demonstrated that male students who participated in the program during Grade 9 were significantly more likely to graduate from high school within 4 years than male students in the control group (81% vs. 63%). Findings suggest that peers can be effective in delivering a school-based, social emotional learning intervention and that it is possible to intervene in Grade 9 to influence the probability of high school graduation.